This invention relates to hoses or flexible pipes, and relates more particularly but not exclusively to hoses or flexible pipes which are adapted to the transport of hydrocarbons.
As used in this specification, the terms xe2x80x9chosexe2x80x9d and xe2x80x9cflexible pipexe2x80x9d are mutually synonymous. A hose (or flexible pipe) is an elongate flexible tube suitable for the transport of fluids (liquids and/or gases), and which can adapt to different paths without permanent deformation, eg. to provide a fluid path between objects which are in relative movement, such as a floating tanker and a production platform anchored on the sea bed. Hydrocarbons produced by undersea wells are frequently chemically and physically aggressive, and hence liable to cause unacceptable damage to transport hoses. Hoses usually require end fittings by which the hose ends may be mechanically anchored and also secured in a fluid-tight manner to a source or receiver of the fluid to be transported by the hose. Such end fittings require to be reliably sealed to the hose both to withstand pressure and to withstand degradation by the fluid transported by the hose.
According to a first aspect of the present invention there is provided a hose or flexible pipe characterised in that the hose or flexible pipe is internally lined with an internal lining comprising a fluoropolymer.
The hose or flexible pipe is preferably formed such that the wall of the hose or flexible pipe is a bonded structure at least in the part of the wall contacted by the internal lining. The wall of the hose or flexible pipe is preferably a fully bonded structure.
The fluoropolymer of the internal lining is preferably at least one fluoropolymer selected from the group of fluoropolymers comprising ETFE (ethyl-tetra-fluoro-ethylene), FEP (fluorinated ethylene propylene), HFP (hexa-fluoro-propylene), and PFA (per-fluoro-alkozyl).
The hose or flexible pipe may comprise reinforcement means which is preferably embedded in the wall of the hose or flexible pipe. The reinforcement means preferably comprises at least one reinforcement selected from the group of reinforcements comprising at least two layers of steel wire helically wound around and along the hose or flexible pipe, or at least one layer of synthetic polymeric textile material which may comprise aramid fibres. The reinforcement means may be embedded in an elastomer which may comprise silicone rubber, the elastomer preferably being reinforced by embedded yarn.
The internal lining of the hose or flexible pipe may itself be internally lined with an collapse-resistant liner which may be in the form of a self-interlocking spiral of steel strip.
According to a second aspect of the present invention there is provided a pressure-actuated seal for sealing the interface between an end fitting mounted on and secured to an end of a hose or flexible pipe and the internal lining of the hose or flexible pipe, characterised in that the seal comprises at least one cavity in the end fitting, the or each said cavity being contiguous with the interface, and in that a respective mass of polymeric material is located in the or each said cavity to be adjacent the interface, wherein the or each said cavity communicates with the bore of the hose or flexible pipe to transfer the pressure of fluid in the bore of the hose or flexible pipe to the respective mass of polymeric material such as to urge the respective mass of polymeric material against the portion of internal lining defining that part of the interface with which the respective cavity is contiguous.
The seal may comprise discrete communication means for communicating the or each said cavity with the bore of the hose or flexible pipe. The discrete communication means may comprise fluid passage means, and where there are a plurality of cavities in the end fitting, the fluid passage means may lead from a given cavity either directly to the bore of the hose or flexible pipe, or indirectly by way of another cavity which itself is directly or indirectly communicated with the bore of the hose or flexible pipe by way of a further fluid passage means.
At least one cavity in the end fitting may extend circumferentially around the fitting, and the respective mass of polymeric material located in said circumferentially extended cavity may be generally toroidal. The or each generally toroidal mass of polymeric material may incorporate a respective reinforcing member which is itself generally toroidaly and preferably embedded in the respective mass of polymeric material.
The polymeric material of the seal means is preferably a fluoropolymer which may be a fluoropolymer selected from the group of polymers comprising ETFE (ethyl-tetra-fluoro-ethylene), PTFE (poly-tetra-fluoro-ethylene), FEP (fluorinated ethylene propylene), HFP (hexa-fluoro-propylene) and PFA (per-fluoro-alkozyl), or a mixture of two or more fluoropolymers selected from said group of fluoropolymers.
In the seal means, the or each said mass of polymeric material may be associated with a respective non-polymeric member disposed between at least the greater part of the respective mass and the inlet or inlets to the respective cavity of the fluid passage means. The or each said non-polymeric member may be formed of sheet metal and be present in or on the respective mass of polymeric material at least in the portion or portions thereof adjacent said inlet or inlets.